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Home , Foul Bay, Straits of Tiran, Tiran Island

OCEANOLOGICA ACTA 1985- VOL. 8- W 4 ~ -----·~-

Red Sea Benthic fishes Community structures The communities of benthic fish Species richness Mer Rouge Ile de Tiran in Foui Bay (Tiran Island, ) Poissons benthiques Structure de la communauté Richesse en espèces

Menachen GOREN, Ehud SPANIER Department of Zoology, George S. Wise Faculty of Life Sciences,Tel Aviv University, Ramat-Aviv 69978 Tel-A viv, . Department of Maritime Civilizations and Center for Maritime Studies, University of Haïfa, Mount Carmel, Haifa 31999, Israel.

Received 11/3/85, in revised form 6/6/85, accepted 7/6/85.

ABSTRACT The study was conducted on benthic communities of fishes in Foui Bay (Tiran Island, Northern Red Sea). 1588 fish assigned to 154 species were collected at six stations. The number of species at each station ranged from 21 to 64. The values of species s diversity (H=- L (Pi log Pi)) were found to be relatively high: 2.0050-5.5500, as i=l were the values of the evenness rate (J =H/Hmax): 0.3742-0.952 8. The values of s similarity between each couple of stations (A/=[2- L IPiJ-PiKI.50]) were found 1=1 to be low: 7.25%-41.38%, as were the proportions of species common to each couple of stations: 10.87-29.59%. The richness of species of the leading families is compared with that of the entire Red Sea and that of the reef community of northern Entedebeer Island. The ecological significance of these findings and the uniqueness of Foui Bay in its tropical surroundings are discussed. Oceanol. Acta, 1985, 8, 4, 471-478. RÉSUMÉ Les communautés de poissons benthiques dans la baie Foui (île de Tiran, Mer Rouge) Cette étude porte sur les communautés benthiques des poissons de la baie Foui (île de Tiran, nord de la Mer Rouge). 1 588 poissons appartenant à 154 espèces ont été récoltés dans 6 stations. Le nombre d'espèces dans chaque station varie entre 21 et s 64. On constate que les valeurs de l'indice de diversité spécifique (H = - L Pi log Pi) i=l sont relativement fortes (2,005-5,550), de même que celles de l'équitabilité (J =H/ Hmax) égales à 0,374-0,953. La similarité entre les stations prises deux à deux (7,25- 41,38 %) ainsi que le pourcentage du nombre d'espèces qui leur sont communes (10.8- 29.59 %) sont faibles. La richesse spécifique des principales familles de la baie Foui est comparée à celle de la Mer Rouge considérée dans son ensemble ainsi qu'à celle de la communauté récifale située au nord de l'île Entedebeer. La signification écologique de ces résultats et la particularité de la baie Foui par rapport à son environnement tropical sont discutées. Oceanol. Acta, 1985, 8, 4, 471-478.

INTRODUCTION features of this small desert island is its inner bay. This bay, known as Foui Bay, reaches deep into the island. The Island of Tiran (Fig. 1) is a part of the complex Since it is protected from the intense currents prevail­ of Midian Islands, situated in the , ling on both sides of the island (Klinker et al., 1976), separating two zoogeographical subdivisions-the Red the water of the bay is relatively calm. These conditions Sea proper in the south and the Gulf of Elat (Gulf of have brought about an ecological environment of a ) in the north. One of the unique geographical large shallow bay, the bottom of which is covered with

0399-1784/85/04 471 08/$ 2.80/(0 Gauthier-Villars 471 M. GOREN, E. SPANIER

Figure 1 Map of Tiran Island showing the locations of the sampling stations. 1, the camp of the first expedition; 11, the camp of the second expedition.

MARSA BHU,BEER

EL·QURIN

TIRAN ISLAND

soft sediment, in contrast to the rest of the island which elima te of the island and its surroundings are of defini te is surrounded by an exensive area of coral reefs and desert character, with extremely high summer tempera­ exposed to intense current and wave action. There are tures and very little, or no precipitation. A constant, a few similar formations in the Gulfs of Elat and Suez, and at times fairly strong northerly wind predominates but ali are much smaller than Foui Bay. The fact that through the Gulf of toward Tiran. There are this island is remote, with no freshwater sources, bas intense currents around the island. Waters are clear prevented human settlement; th us, the underwater habi­ with a low primary production (Levanon-Spanier et tats remain completely undisturbed by man-made acti­ al., 1979). These conditions are ideal for the deve­ vity. These circumstances provide a rare opportunity lopment of fringing coral reefs. Off the southern coast for the faunistic and zoogeographical study of a unique of the island, where the offshore submarine slope is ecological formation typical to the Midian Islands, steep, the fringing reef rarely exceeds 50 rn in width which have not been studied up to the present. and sometimes is even entirely absent. The coasts with In addition to the faunistic information, the Tiran less submarine offshore slopes have correspondingly project permits a quantitative analysis of the fish com­ broader fringing reefs. The most extensive reefs are off munity of Foui Bay. Although the fish fauna of the the northern peninsula of the island which Schick Red Sea bas been investigated for about 200 years, and (1958) suggested should be classified as shoal reefs. more than a thousand papers and books report this There are also several developed coral formations in activity (Dor, 1984), only a few studies of community the opening of Foui Bay. Inside this bay, however, structure have been made. Fishelson et al., (1973), there are only very narrow reefs on the north coast, Bouchon-Navaaro (1980) and Bouchon-Navaro and and only small and flat coral outcrops along the Harmelin-Vivien ( 1981) described the species composi­ southern and eastern margins. Physical processes, such tion of certain families living in coral reefs. The single as currents and waves inside the bay, are of much comprehensive quantitative analysis of a fish commu­ smaller dimensions relative to the marine environment nity in the Red Sea was published by Clark et al. outside this gulf basin. Thus, the bottom of the bay is (1968). The present study throws more light upon this covered with a layer of soft sediment. 1t is unique also ecological aspect. with areas of dense growth of soft and delicate sea grass of the species Halophila stipulacea, H. ovalis, and H alodule uninervis (Lipkin, 1977). The latter is the pre­ ferred food of the Red Sea dugong Dugong dugong AREA OF STUDY (Lipkin, 1975) a marine mammal observed several times in Foui Bay including the present expedition. The Island of Tiran (Fig. 1) measures sorne 11 km north-south and 12 km east-west, with an area of 59 km2 (Schick, 1958). The highest point of the island is 502 rn above sea level (Goldberg, 1958), with a steep METHODS AND MATERIALS summit of ridges running along the southern coast of the island. North of this ridge, on either side of Foui The fish communities around Tiran Island were studied Bay, extends a plain which occasionally bas features of at 9 stations by the members of two expeditions conduc­ modest relief. The neck connecting the two parts of ted by the authors (Fig. 1). The first expedition the island is a low billy ridge (Goldberg, 1963). The (9 persons) took place from 1-6 June 1981, and the

472 FISH COMMUNITIES OF (RED SEA) second (10 persons) from 21-26 September 1981. The Station 5 (4 June, 1981) present paper covers the data of the 6 stations inside Foui Bay (stations 4-9, Fig. 1). Shallow (0-1.5 rn) water with mostly rocky, and par­ tially sandy bottom, covered with small coral heads of The method of collecting fish in the various stations the genus Stylophora and sea grass of the genera was based on poisoning with pronoxfish (rotenon). The Halophila and Halodule. poison mixture - pronofish +sand - was prepared a short time before use to prevent spoilage by oxidation. Station 6 (22 September, 1981) The mixture was released close to the bottom by Shallow water with maximum depth of 1.5 rn with SCUBA divers. The fish were collected by skin and sandy bottom and low knolls, consisting of various SCUBA divers and preserved in formalin (4%). Large specimens (with TL>8 cm) were also injected with types of corals. formalin. The sampled fishes were identified and their total length was measured. The number of specimens Station 7 (29 September, 1981) per species were counted for each station. This was Depth 9-12 m. Sandy trenched bottom with coral done when the material was deposited in the Zoological knolls, coral plants and branched corals. Museum of Tel A vi v University. Bottom sediments were sampled at sorne of the stations. Station 8 (23 September, 1981) Grain size analysis of these samples was carried out Depth 8-10 m. The steep edge of a narrow fringing reef with the use of sieves. The insoluble residue of these with a sandy bottom at the foot of the escarpment. samples was also determined. Sediment analysis was performed at the Center for Maritime Studies, Uni­ Station 9 (24 September, 1981) versity of Haifa. Depth 0.5-1.5 m. Flat sandy bottom with a few flat The species diversity (H) for each station was calculated rocks broken by crevices and holes, covered partially using the formula offered by Shanon and Weaver s with various types of corals. A histogram representing (1963): H=- L (Pilog Pi), where Pi is the propor- the particle size of stations 4, 6 and 8 are presented in i=l Figure 2. tion of the ith species in the sample and S = is the ca STATION 4 number of species in the sample. The evenness rate (J) • STATION 6 was calculated as H/Hmax where Hmax is estimated 0 STATION 8 as log S. For further mathematical explanations see Pielou (1966; 1969). 30 The communities of the six stations were compared by both measures: species composition and degree of similarity. Species composition comparisons were made 20 for each pair of stations by calculating the percentage of species common for both stations (for example: if species A, B, C were found in station 1 and species B, C, D were found in station 2, then the percentage is 50% [2/4]). The degree of similarity (At) between two stations compared was calculated by the formula s Af=( 2-;~ IPiJ-PiKI.50) The degree of simila- 1051' 1801' 3541' 7101' 1.4mm 2.8mm 5.66mm Insoluble 1 Particle size residue rity (Aj) is expressed in percentages; PiJ and PiK are Figure 2 the relative abundance of the ith species in J and K Histograms representing an ana/ysis of sediment sampled in stations communities respectively; 1 1 is a sign for absolute 4, 6, 8. value. (for further details see Goren 1979; 1980). RESULTS 1588 fish belonging to 154 species were collected at the DESCRIPTION OF THE STATIONS six stations of Foui Bay. The list of species, the number of individuals per species and the size range of the fish collected in each station are presented in Table 1. The locations of the various stations are shown in Figure 1. Co~parisons of the six stations

Station 4 (3 June, 1981) The summary, for each station, of the number of indivi­ duals, number of species, species diversity and the rate Depth 6-9 rn, flat sandy bottom with high stem eveness is presented in Table 2. As indicated in Table 2, mushroom-like branched coral formation consisting the values of species diversity and evenness rate are mainly of the genus Acropora. remarkably high (with the exception of station 6).

473 M. GOREN. E. SPANIER

Table 1 Fish species collected in Foui Bay. N=number of specimens; Range=range offish sizes (totallength in mm).

Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 ...--..- ...-..._ --N Range N Range N--- Range --N Range N Range N Range Clupeidae Etrumeus teres (De Key, 1842) 12 24-52 3 26-50 Sardinella melanura (Curvier, 1829) 20 15-39 35 33-45 12 35-40 Synodontidae Synodus variegatus (Lacepede, 1821) 98 2 56-71 2 60-115 6 85-115 Saurida undosquamis (Richardson, 1848) 2 55-95 3 68-80 2 60-63 Saurida gracilis (Quoy, Gaimard, 1824) 7 80-133 6 46-128 Muraenidae Lycondontis undulatus (Lacepede, 1803) 320 Congridae Conger cinereus Ruppell, 1830 183 4 220-295 Ariosoma scheelei (Stromman, 1896) 32 81-258 Ophichthidae Muraenichthys schultzei Bleeker, 1857 3 105-142 Muraenichthys gymnotus Bleeker, 1857 170 8 96-145 Hemiramphidae Hyporhamphus affinis (Gunther, 1866) 194 4 74-76 Hemiramphus far (Forskal, 1775) 390 Belonidae Tylosurus crocodilus (Peron, Le Suer, 1821) 7 320-450 Atherhinidae Allanetta afra (Peters, 1865) 10 40-46 Apogonidae Arachamia lineolata (Cuvier, Valenciennes, 1828) 23 28-72 42 33-66 53 27-69 Arachamia fucata (Cantor, 1850) 3 73-83 Apogon cyanosoma Bleeker, 1853 6 49-56 2 46-50 41 3 39-51 Apogon annularis Ruppell, 1829 5 25-41 Apogonichthyoides sp. 1 63 1 45 5 64-75 Cheilodipterus bipunctatus (Lachner, 1951) 2 56-68 55 7 26-75 19 22-53 18 29-48 28 13-78 Cheilodipterus caninus Smith, 1949 1 131 Cheilodipterus lachneri Klausewitz, 1959 3 113-126 Cheilodipterus quinquelineatus Cuvier, 1828 7 40-82 Apogon angustatus (Smith, Radcliffe, 1911) 1 36 Fowleria aurita (Valenciennes 1831) 1 58 1 53 Apogon fleurieu (Lacepede, 1902) 1 34 1 25 Apogon multitaeniatus Cuvier, 1828 3 25-97 Apogon kallopterus Bleeker, 1856 8 19-32 4 34-66 Siphamia permutata Klausewitz, 1966 1 46 2 25-42 12 17-56 10 14-43 Nemipteridae Scolopsis sp. 12 43-59 Gerridae Gerres sp. 4 48-60 Letarinidae Lethrinus obsoletus (Forskal, 1775) 3 75-101 Sparidae Acanthopagrus bifasciatus (Forskal, 1775) 2 45-300 Rhabdosargus haffara (Forskal, 1775) 1 89 Rhabdosargus sarba (Forskal, 1775) 3 115-145 Mullidae Pseudupenaeus rubescens (Lacepede, 1801) 3 55-95 Pseudupenaeus macronema (Lacepede, 1801) 2 69-76 Pseudupenaeus forskali Formanoir, Guese 1976 24 66-109 1 74 5 46-73 Chaetodontidae Chaetodon austriacus Ruppel, 1806 4 46-58 1 107 4 66-118 122 Chaetodon auriga Forskal, 1775 3 66-154 2 67-135 Chaetodon paucifasciatus Ah!, 1923 2 75-89 2 31-93 2 75-94 Chaetodon fasciatus Forskal, 1775 1 161 Chaetodon lineolatus Cuvier, Valanciennes, 1831 2 19-35 56 Heniochus intermedius Steindachner 1893 66 69 94 Pomacanthidae Arusetta asfur (Forskal, 1775) 155 Pygolites diacanthus (Boddaert, 1772) 170 Pempheridae Pempheris oulensis (Cuvier, 1837) 12 42-53 Pomacentridae Abudefduf sexfasciatus (Lacepede, 1802) 2 32-57 Amb/yg/yphidodon flavilatus Allen, Randall1978 14 20-82 15 24-68 Amphiprion bicinctus Ruppell1828 65 24 4 10-55 Chromis caerulea (Cuvier, 1830) 4 53-62 10 16-28 Chromis dimidiata (Klunzinger, 1871) 26 26-62 Chromis pembae Smith, 1960 2 44-65 12 28-55 Chromis ternatensis (Bleeker, 1856) 21 Chrysiptera annulata (Peters, 1855) 25 15-60 1 46 Dascyllus aruanus (L. 1758) 2 54-70 Neopomacentrus xanthurus (Allen, Randall, 1978) 16 31-61 Paraglyphidodon melas (Cuvier, 1830) 2 35-46 Pomacentrus aquilus Allen, Randall1978 4 16-35 5 26-40 Pomacentrus albicaudatus Baschieri-Salvadori, 1955 25 18-56 5 26-58 Pomacentrus sulfureus Klunzinger, 1871 4 20-42

474 FISH COMMUNITIES OF FOUL BAY (RED SEA)

Table 1 Fish species collected in Fou/ Bay. N=number of specimens; Range=range offish sizes (tota//ength in mm).

Station 4 Station 5 Station 6 Station 7 Station 8 Station 9 N Range N Range N Range N Range N Range ----N Range Pomacentrus trichourus Playfair, Gunther, 1866 67 1 46 Pomacentrus tri/ineatus Cuvier, 1830 7 37-85 21 34-69 Holocentridae Sargocentron diadema (Lecepede, 1802) 2 77-83 4 76-90 14 66-113 7 63-93 12 75-98 26 46-157 Flammeo sammara (Forskal, 1775) 2 45-62 7 35-105 1 36 6 36-102 Sargocentron lacteogutattum (Cuvier, 1829) 1 67 2 38-80 Sargocentron spinifer (Forskal, 1775) 1 320 340 Myripristis murdjan (Forskal, 1775) 70 Syngnathidae Ha/icampus macrorhynchus Bamber, 1915 105 Corythoichthys schultzi Herald, 1953 6 109-112 Corythoichthys flavofasciatus (Ruppell, 1938) 70 Siokunichthys sp. 68 Doryrhamphus exicscus Kaup, 1853 2 27-31 Lissocampus sp. 52 3 32-74 Micrognathus andersonii (Bleeker, 1858) 26 A ploactinidae Ptarmus gallus (Kossman, 1877) 57 Serranidae Epinephelus summana (Forskal, 1775) 1 65 2 255-365 Epinephelus chlorostigma (Valenciennes, 1828) 3 85-100 10 80-130 Epinephelus fuscoguttabus (Forskal, 1775) 2 138-142 280 260 Epinephelus merra (?)(Bloch, 1853) 178 Epinephelus tauvina (Forskal, 1775) 1 800 Epinephelus sp. 2 480-490 Pseudochromidae Pseudochromis o/ivaceus Ruppell, 1953 2 37-56 29 45-87 6 22-65 3 25-28 10 12-53 2 24-30 Pseudochromis flavivertex Ruppell, 1935 3 36-57 1 64 1 43 9 26-56 6 32-60 9 42-76 Pseudochromis fridmani Klausewitz, 1968 2 23-32 Pseudochromis sp. 2 33-41 5 49-55 16 30-68 9 46-57 Pseudochromis springeri Lubbock, 1975 3 20-56 25 30-65 10 31-36 Childichthys rubiceps Lubbock, 1975 7 15-42 1 36 Plesiopsidae Plesiops nigricans (Ruppell, 1828) 36 2 17-19 Carangidae Carandoides fulvoguttabus (Forskal, 1975) 2 296-340 Callogobius clarki (Goren, 1978) 1 31 6 45-56 4 23-53 2 27-47 Amblygobius albimaculatus (Ruppell, 1838) 71 2 16-55 8 53-105 2 38-57 8 16-75 Amblygobius klausewitzi (Goren, 1978) 3 37-46 2 36-41 3 26-44 Istigobius spence (Smith, 1947) 8 28-74 2 56-60 lstigobius ornatus (Ruppell, 1830) 1 33 Asterropterix semipunctatus Ruppell, 1830 24 17 14-45 2 28-31 4 18-38 Priolepis avidori (Goren, 1978) 29 6 14-24 9 21-24 Paragobiodon echinocephalus (Ruppell, 1830) 7 23 Paragobiodon xanthosoma (Bleeker, 1852) 3 13-24 Paragobiodon sp. 1 20 Gobiodon reticulatus Playfair, Gunther, 1866 6 9-36 14 1 22 Gnatholepis cauerensis (Bleeker, 1853) 1 46 2 14-47 Trimma flavicaudata (Goren, 1980) 10 Trimma mendelssohni (Goren, 1978) 2 18-24 Vanderhorstia delagoae (Barnard, 1937) 6 34-78 Lioteres vu/gare (Klunzinger, 1871) 1 27 Hetere/eotris diademata (Ruppell, 1830) 9 Coryoga/ops sufensis Goren, 1979 4 17-27 25 6 22-24 Éviota distigma , Seale, 1906 1 16 10-17 1 15 Eviota zebrina Lachner, Karnella, 1978 9 13-15 Eviota guttata Lachner, Karnella, 1978 1 9 Eviota pardalota Lachner, Kamella, 1978 8 12-17 Eviota sebreei Jordan, Seale, 1905 24 Fusigobius longispinus Goren, 1978 38 Amblyeleotris steinitzi (Kiausewitz, 1974) 27 Pleurogicya prognatha Goren, 1984 10 25-36 Siganidae Syganus luridus (Ruppell, 1829) 2 55-57 Syganus rivulatus (Forskal, 1775) 22 38-105 46 Syganus stel/atus (Forskal, 1775) 1 260 2 165-170 Labridae Pseudocheilinus hexataenia (Bieeker, 1857) 2 38-52 Cheilinus sp. 25 65-125 W etmorella sp. 1 54 Pteragogus cryptus Randall, 1981 50 Scaridae Scarus gibbus Ruppell, 1829 27 Scarus niger Forskal, 1775 124 Scarus sp. 40 5 55-95 Congrogadidae Haliophis guttatus (Forskal, 1975) 2 30-39 2 40-103 7 40-113 2 36-89 Tripterygiidae Enneapterygius destai Clark, 1980 26 2 27-28 Enneapterygius pusillus Ruppell, 1835 7 25-28

475 M. GOREN, E. SPANIER.

Table 1 Fish species collected in Foui Bay. N=number of specimens; Range=range offish sizes (totallength in mm).

Station 4 Station 5 Station 6 Station 7 . Station 8 Station 9 . r ! --... - .. _..._._ - .. - N Range N Range N Range N Range N Range N Range

Blennidae Ecsenius nalolo Smith, 1959 1 35 Ecsenius frontalis (Valenciennes, 1836) 1 • 27 4 24-61 2 56-74 37 Ecsenius gravieri (Pellegrin, 1906) 2 54-67 Enchelyurus petersi (Kossmann, Rouber, 1887) 3 35-52 4 45-53 Plagiotremus townsendi (Regan, 1805) 1 32 Cirripectus variolosus (Valenciennes, 1836) 5 26-54 Petroscirtes mitratus Ruppell, 1830 10 23-56 34 7 17-40 Salarias fasciatus (Bloch, 1886) 4 25-68 Meiacanthus nigrolineatus Smith-Vaniz, 1969 2 42-54 2 33-35 16 36-47 8 20-51 5 28-34 Gobiidae Valenciennea sexguttata (Valenciennes, 1837) 16 82-125 22 22-80 Seyche/lea hectori Smith, 1957 60 25 16-53 Callogobius irrasus (Smith, 1959) Callogobius dori Goren, 1980 11 17-32 Acanthuridae Acanthurus nigrofuscus (Forskal, 1775) 1 46 Zebrasoma veliferum (Bloch, 1795) 3 21-31 2 32-34 3 240-296 Nasco unicornis (Forskal, 1775) 1 460 Callionymidae Callionymus filamentosus Valenciennes, 1837 21 44-89 11 35-74 Bothidae Bothus pantherinus (Ruppell, 1830) 4 29-76 Bothus sp. 1 95 Arnoglossus intermedius (Bleeker, 1866) 82 3 22-93 Balistidae Pseudobalistes fuscus (Bloch, Schneider, 1801) 3 70-98 Monacanthinae Oxymonacanthus halli Marshall, 1952 2 35-46 Tetraodontidae Arothron hispidus (L, 1758) 1 340 Canthigaster margaritatus (Ruppell, 1829) 23 21-53 9 20-28 25 18-59 Canthigaster pygmaea Allen, Randall, 1977 2 38-52 3 33-46

Station 6 the opening of the bay. This locality has an advantage This station is characterized by low values of species as far as water circulation and water clearance (little diversity and evenness rate. This is probably due to the sedimentation) are concerned. existence of a barrier reef, south of the site, which Stations 8 and 9 prevents free circulation of water. It is also due to the fact that the substratum of this area is sandy and very The high species diversity and evenness rate found in poor in sessile invertebrates, such as corals (due to the these stations are also an outcome of the high variety of extreme ecological conditions). ecological niches and relatively good water circulation. The results of the comparison between stations 4-9 are Station 4 presented in Table 3. This comparison includes both: High values of the diversity of species and the evenness the degree of similarity (in percent.) and the percentage rate are to be expected in this complex area, but since of common species occurring in each pair of stations. the number of fish collected in this station was relati­ The highest similarity is found between stations 6 and vely low, one should be cautious when referring to this 9. This is probably due to the similarity of the biotopes, station. e. g. shallow water and sandy substratum. The relatively low percentage of common species in the two communi­ Station 5 ties is probably due to the difference in the richness of Like station 6, this is an area of shallow water and species between the two. The second couple ranked are sandy substratum, but unlike the latter station, there · stations. 6 and 8. These stations also have the highest is no barrier reef here to prevent free circulation of water. Coral colonies, mostly of the species Stylophora Table 2 pistillata, are very abundant and extend almost to the Diversity parameters of fish communities in Foui Bay (stations 4-9). shore line. This increases the complexity of the bietope N, numb~ of individuals; S, number of species; H, species diversity and as a result, the species diversity and evenness rate. ( H=- L (Pi log P1)); J, evenness rate (J=H/Hmax). 1•1

Station 7 Station 4 5 6 7 8 9 This station has the highest species diversity and even­ N 49 276 147 341 410 392 ness rate amongst the stations studied in Foui Bay. s 21 38 47 64 61 63 This is explained by the fact that this station has a H 4.1170 4.0750 2.0050 5.5500 4.7277 5.2185 very complex biotope, as weil as by its proximity to J 0.9528 0.7765 0.3742 0.9321 0.8036 0.8730

476 FISH COMMUNil'IES OF FOUL BAY (RED SEA)

Table 3 shallow water fish, pelagie and benthic species, etc. The Comparisons between benthic fish communities of Fou/ Bay (stations concentration of about 15% of the fish species of the 4-9). The upper right hand part represents the degree of similarity (in Red Sea in a very restricted area of relatively shallow percent). The lower /eft hand part of the table shows the percentage of the common species occurring in each pair of stations (in parenthesis, water in Foui Bay (Tab. 1) requires attention. It is the number of common species above the total number of species in suggested that this richness is due to three main both communities). reasons: 4 5 6 7 8 9 Station (%) (%) (%) (%) (%) (%) The location of Tiran Island 4 13.03 20.50 18.00 20.00 16.50 5 11.76 7.25 12.35 19.50 20.45 This island is positioned very close to a point where (5/51) the shallow, sandy and the deep-water 6 21.56 16.17 23.55 33.95 41.38 Gulf of Elat open into the Red Sea proper. The high (ll/51) ( 11/68) 7 11.53 10.87 22.99 27.60 26.85 evaporation rate in the Gulf of Elat and the wind (9/78) (10/92) (20/87) regime in this area, together with tidal currents, are 8 14.28 11.76 28.20 29.59 30.98 (10/70) (10/85) (22/78) (29/98) responsible for the intense constant currents along 9 13.88 18.60 25.30 24.51 21.21 Tiran Island flowing into and out of the Gulf of Elat (10/72) (16/83) (21/78) (25/102) (21/99) (Klinker et al., 1976). These currents enrich the Island with fish larvae and other kinds of plankton.

Tbe existence of many biotopes differing from eacb other percentage of common species. This similarity is proba­ in tbe same neighbourhood bly the result of the two stations being very close to each other (less than 1 km apart). The least similarity Each of these biotopes (except station 6) are of high was found between stations 5 and 6. These stations complexity which is expressed in the richness of fish represent frontier regions, but of different types. The species and in the high species diversity as demonstra­ common fish found in these two areas are mostly fish ted in Table 3. living in or around corals. A low degree of similarity was also found in the couple 5 and 7. The differences could be the result of the stations being far away from each other and therefore being representative of a Table 4 A comparison of the numbers of species of each "leading" family in completely different type of biotope. the Red Sea (based on Dor, 1984) with the numbers found in Fou/ Bay and Entedebeer (Clark et al., 1968). Comparison of Foui Bay with the entire Red Sea and northem Entedebeer Island (Southern ked Sea) Total Foui Bay Entedebeer

No. of ~ The number of species of each family found in Fout species ------percent Percent Bay was compared with the number of species of that in the No. of of the No. of of the family in the entire Red Sea. The ratio was converted Farnily Red Sea species total species total into percentage (No. of species in Foui Bay x 100/No. Muraenidae 17 1 5.8 3 17.6 of species in Red Sea (Dor, 1984). The resutts referring Ophich thidae 15 2 13.3 Congridae 10 2 20.0 to the teading famities (8 or more species in the Red aupeidae 12 2 16.6 8.3 Sea) are presented in Table 4. This table indicates that Synodontidae 9 3 33.3 the famities Pomacentridae, Apogonidae, Pseudochro­ Antennariidae 12 Holocenbridae 8 5 62.5 1 12.5 midae, Hotocentridae and Gobiidae appeared in high Syngnathidae 24 7 29.1 3 12.5 proportiohs, while the Labridae, Scaridae, Scorpaeni­ Scorpaenidae 33 2 6.0 2 6.0 Platycephalidae 9 1 11.1 dae, Lutjanidae, Letrinidae, Haemulidae, Muraeanidae, Serranidae 33 6 18.1 3 9.1 Callionymidae and Monacanthidae are poorly represen­ Pseudochrornidae 10 6 60.0 1 10.0 ted. The data published by Clark et al. (1968) were Pornacentridae 39 16 41.0 8 20.5 Labridae 65 3 4.6 10 15.3 compared with those of Fout Bay and were added to Scaridae 17 3 17.6 8 47.0 Table 4. The families Labridae, Scaridae, Blenniidae, Blenniidae 41 9 21.9 14 34.1 Tripterygiidae and Acanthuridae appeared in Entede­ Tripterygiidae 11 2 8.3 4 36.3 Callionyrnidae 12 1 8.3 beer (Dahlak Archipelago) in higher proportions than Gobiidae 90 30 33.3 20 22.2 in Foui Bay, white the families Holocentridae, Acanthuridae 15 3 20.0 5 33.3 Bothidae 9 3 33.3 Pseudochromidae, Pomacentridae and Tetradontidae Apogonidae 39 15 38.4 7 17.9 appeared in lower proportions. Carangidae 32 1 3.1 4 12.5 Lutjanidae 26 1 3.8 Nemipteridae 9 11.1 1 11.1 Haernulidae 18 DISCUSSION AND CONCLUSIONS Lethrinidae 12 1 8.3 2 16.6 Sparidae 12 3 25.0 1 8.3 Chaetodontidae + The Red Sea is a tropical sea, and like the other parts Pornacanthidae 25 8 31.2 6 24.0 Mullidae 11 3 27.2 2 18.1 of the Indo-Pacific complex, it is characterized by a Cynoglossidae 11 rich marine fauna. Dor (in press) lists about 1 000 valid Balistidae 11 1 9.0 9.0 fish species in the Red Sea. This count includes fish Monocanthidae 14-15 1 7.1 7.1 inhabiting a wide spectrum of biotopes: deep sea and Tetraodontidae 13 3 23.0 7.6

477 M. GOREN. E. SPANIER

The topography of the island and the coral reefs surroun­ The results of the present research of the benthic fish ding it communities of Foui Bay in Tiran Island, demonstrate the richness of this unique area. Although much data They protect Foui Bay from storms and high turbidity, bas been accumulated on the structure of these commu­ yet enable the circulation of water inside the bay. Thus, nities, the research is still far from being complete, this bay becomes a shelter for various fish species which especially concerning the extensive coral reefs surroun­ are protected there from rough sea conditions. ding Tiran Island. Foui Bay itself is a unique demonstration of the effect of environmental factors on species diversity and rate of evenness. Geomorphological structures, bottom sedi­ Acknowledgements ments, the degree of water circulation and clarity and the complexity of the rest of the fauna and flora determine the species diversity of the ichthyofauna in We would Iike to thank the following members of the sites which may be in very close proximity. The more two expeditions for their useful assistance in the diving complex a station is concerning hermatypic corals and operation and other field work: O. Kerman, E. Galili, other sessile invertebrates, the more niches it can offer A. Diamant, D. Golani, A. Kushnir, A. Keler, to incoming adult fishes and fishes in the young stages. A. Goren. Thanks are due also to A. Lucie as weil as lncreasing water circulation may increase food supply, to other members of the Israel Nature Reserves as weil as supply new potential resident fish, especially Authority for their aid in organizing the expeditions. juvenile forms. The consideration of geographical dis­ We are also grateful to M. Tom for reviewing the manuscript. tance between sites cornes only after the above accounts concerning space and food. Geographical proximity is more important when considering the degree of simila­ REFERENCES rity than in respect of species diversity. The uniqueness of Foui Bay is expressed not only in the richness of species, but also by the species composi­ Boucbon-Navaro Y., 1980. Quantitative distribution of the Caetodon­ tidae on a fringing reef of the Jordanian coast (, Red tion. As we see in Table 4, Foui Bay is characterized Sea), Tethys, 9, 3, 24-251. by a typical fauna which is not a "miniature" of the Boucbon-Navaro Y., Harmelin-Vivien M.-L., 1981. Quantitative distri­ Red Sea, and differs also from Entedebeer Island bution of herbivorous fishes in the Gulf of Aqaba (Red Sea), Mar. (Southern Red Sea). Families such as Labridae, Scari­ Biol., 63, 79-86. ClarkE., Ben-Tuvia A., Steinits H., 1968. Observations on a coastal dae, Cynoglossidae, Lutjanidae, Haemulidae and Lethri­ fish conununity, Dahlak Archipelago, Red Sea, Sea Fish. Res. Stn nidae are absent or poorly represented, white other Haïfa, Bull., 49, 15-31. families such as Pomacentridae, Apogonidae, Dor M., 1984. Check list of the fishes of the Red Sea, The Israeli Gobiidae, Pseudochromidae and Holocentridae are Academy of Sciences and Humanities, Jerusalem, 437 p. Fisbelson L., Popper D., Avidor A., 1974. Biosociology and ecology represented by many species. The rareness of families of pomacentrid fishes around the {northern Red such as Haemulidae, Lethrinidae and Lutjanidae in Sea), J. Fish Biol., 6, 119-133. Foui Bay is understandable: the members of these fami­ Goldberg M, 1958. The geology of Tiran Island, M. Sei. Thesis, lies can not be considered as typical coral reef fishes, Dep. Geology, The Hebrew University, Jerusalem, 48 p. Goldberg M, 1963. The Geology of Tiran Island, Israel J. Earth but the poor. representation of the Labridae, Scaridae Sei., 12, 83-84. and Acanthuridae requires an explanation. Most of Goren M., 1979. Succession of benthic community on artificial the species of the Ieading families in Foui Bay are substratum at Elat (Red Sea), J. Exp. Mar. Biol. Ecol., 38, 19-40. characterized by three behavioural-ecological aspects. Goren M, 1980. Development of benthic community on artificial substratum at Ashdod (Eastern Mediterranean), Oceanol. Acta, 3, They are found in coral reefs or their neighbourhood, 275-283. they remain in relatively small territories and they feed Klinker J., Reiss Z., Kropacb C., Levanon L, Harpaz H., Haliez H., mostly on small invertebrates (infrequently on small 1976. Observations on the circulation pattern in the Gulf of Elat fish). We suggest that the ecological conditions in Foui (Aqaba), Red Sea, Israel J. Earth-Sci., 25, 85-103. Levanon-Spanier L, Padan E., Reiss Z., 1979. Primary production in Bay as described in the chapter "Area of study", and a desert-enclosed sea - the Gulf of Elat (Aqaba), Red Sea, Deep­ especially the stability of the abiotic conditions, permit Sea Res., 26, 673-685. the development of an invertebrate fauna which can Lipkin Y., 1975. Food of the Red Sea Dugong (Mammalie: Sirenia) support a rich and diversified fauna of predatory fishes. from Sinaï, Israel J. Zoo/., 24, 81-98. Lipkin Y., 1977. Seagrass vegetation of Sinai and Israel, in: Seagrass In contrast to this, the fish fauna of the coral reefs ecosystems, edited by C. S. McKoy and C. C. Helffreich, Marcel, facing the sea at northern Entedebeer Island includes Dekker, 264-293. many species of the families Labridae, Scaridae and Pielou E. L., 1966. Shanon's formula as a measure of specifie diversity: its use and misuse, Am. Natur., 100, 463-465. Acanthuridae which move relatively long distances Pielou E. L., 1969. An introduction to mathematical eco/ogy, Inter­ during their daily activity and whose diet is composed science Pub!., New York, 286 p. of a high proportion of algae ( except Labridae, the diet Scbiek A. P., 1958. Tiran: the straits, the island and its terraces, of which is comprised mainly of small invertebrates Israel Exp/or. J., 8, 120-130; 189-196. Shanon C.E., Weaver W., 1963. The mathematical theory of communi­ associated with algae). cation, Univ. Illinois Press, 117 p.

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